// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/at_exit.h"
#include "base/command_line.h"
#include "base/files/file.h"
#include "base/files/file_util.h"
#include "base/strings/string_number_conversions.h"
#include "net/spdy/fuzzing/hpack_fuzz_util.h"
#include "net/spdy/hpack/hpack_constants.h"
#include "net/spdy/hpack/hpack_encoder.h"
#include "net/spdy/spdy_protocol.h"

namespace {

// Target file for generated HPACK header sets.
const char kFileToWrite[] = "file-to-write";

// Number of header sets to generate.
const char kExampleCount[] = "example-count";

} // namespace

using net::HpackFuzzUtil;
using std::map;
using std::string;

// Generates a configurable number of header sets (using HpackFuzzUtil), and
// sequentially encodes each header set with an HpackEncoder. Encoded header
// sets are written to the output file in length-prefixed blocks.
int main(int argc, char** argv)
{
    base::AtExitManager exit_manager;

    base::CommandLine::Init(argc, argv);
    const base::CommandLine& command_line = *base::CommandLine::ForCurrentProcess();

    if (!command_line.HasSwitch(kFileToWrite) || !command_line.HasSwitch(kExampleCount)) {
        LOG(ERROR) << "Usage: " << argv[0]
                   << " --" << kFileToWrite << "=/path/to/file.out"
                   << " --" << kExampleCount << "=1000";
        return -1;
    }
    string file_to_write = command_line.GetSwitchValueASCII(kFileToWrite);

    int example_count = 0;
    base::StringToInt(command_line.GetSwitchValueASCII(kExampleCount),
        &example_count);

    DVLOG(1) << "Writing output to " << file_to_write;
    base::File file_out(base::FilePath::FromUTF8Unsafe(file_to_write),
        base::File::FLAG_CREATE_ALWAYS | base::File::FLAG_WRITE);
    CHECK(file_out.IsValid()) << file_out.error_details();

    HpackFuzzUtil::GeneratorContext context;
    HpackFuzzUtil::InitializeGeneratorContext(&context);
    net::HpackEncoder encoder(net::ObtainHpackHuffmanTable());

    for (int i = 0; i != example_count; ++i) {
        net::SpdyHeaderBlock headers = HpackFuzzUtil::NextGeneratedHeaderSet(&context);

        string buffer;
        CHECK(encoder.EncodeHeaderSet(headers, &buffer));

        string prefix = HpackFuzzUtil::HeaderBlockPrefix(buffer.size());

        CHECK_LT(0, file_out.WriteAtCurrentPos(prefix.data(), prefix.size()));
        CHECK_LT(0, file_out.WriteAtCurrentPos(buffer.data(), buffer.size()));
    }
    CHECK(file_out.Flush());
    DVLOG(1) << "Generated " << example_count << " blocks.";
    return 0;
}
